Just in time for the start of caucus/primary season, Ray La Raja and Jonathan Rauch have this substantial essay out from Brookings. Here is the summary and table of contents for the piece:

Summary

Presidential-nominating contests in both major political parties are at risk of producing nominees who aren’t competent to govern and/or don’t represent a majority of the party’s voters. Raymond La Raja and Jonathan Rauch argue this is a result of the declining role of party insiders in the nomination process and call for the reversal of that trend. Primaries function best, they claim, when voters and party professionals work in partnership.
Table of Contents
I. Introduction
II. The history of presidential primaries
III. Problems with the present process
IV. The promise of professional vetting
V. Proposed reforms